On the other hand, making a title too long and descriptive is annoying too. Sometimes the question title does not need to describe the entire context of the question, even though sometimes they are edited to do just that. :-)
– Aaron Bertrand♦May 9 '12 at 20:41

Yes, they should, as should poorly worded but cogent questions. There are quite a lot of questions posed by inarticulate OPs (first langauge C) that are poorly worded and difficult to understand but are actually sensible questions. Editing the questions and titles to clarify is entirely sensible as it makes the question more useful to other readers as well.